Taper tension web winding machine

ABSTRACT

A taper tension winding machine for winding a web of sheet material, particularly paper or paperboard, on a motor driven take-up core in a manner such that the web tension progressively diminishes according to a programmed function of the increasing web roll diameter, i.e., taper ratio, to prevent circumferentially and axial creep of the inner layers of the roll and permanent elongation of the web. The web tension is regulated by a fluid-pressure-actuated web tensioning mechanism including a fluid pressure regulating valve which is progressively adjusted in relation to the increasing roll diameter to vary the fluid pressure to the tensioning mechanism in such a manner as to achieve the programmed taper ratio. The web roll drive motor may also be regulated to increase the DC electrical motor speed range and reduce the DC motor torque at the beginning of a new rewind roll to permit the use of a relatively small motor. A taper tension control for the winding machine.

14 1 Oct. 31, 1972 on a ng to a ng web roll prevent circumferentially layers of the roll and perng machine for winding a web of particularly paper or paperboard web. The web tension is pressure-actuated web tensioning a fluid pressure regulating val which is progressively adjusted in relation to the increasing roll diame Primary Examiner-George F. Mautz MACHINE Assistant Examiner-Edward J. McCarth [72] lnventors: Bernard J. Welsclr, Downey; James Atwmey Fo"est Lluy A. Shafer, Stanton, both of Calif. [57 1 ABSTRACT [73] Assignee: Western Corporaton, Lyn- A mper tension windi wood Cahf' sheet material,

Sept, 14, 1970 motor driven take-up core in a manner such that the web tension progressively diminishes accordi programmed function of the increasi diameter, i.e., taper ratio, to

242/7553, 242/675, 242/7551 and axial creep 9 the inner .B65h /22, Bh 25/04 elongauop of the 242/755, 75.53, 75.45, 67.5, regulated y a u 242 5 mechanrsm rncludrng References Cited ter to vary the fluid pressure to the tensioning mechanism in such a manner as to achieve UNITED STATES PATENTS the programmed taper ratio. The web roll drive motor may also be regulated to increase the DC electrical United States Patent Welsch et al.

1541 TAPER TENSION WEB WINDING [22] Filed:

[21] Appl. No.: 71,821

[52] US. Cl.

[51] Int.

[58] Field ofSearch.....

3,083,602 4/1963 Obensham......1...242/75.53 X motor speed range and reduce 2ha DC motor torque at Douglas..................242/ the o new e d roll to the use of 3,460,776 8/1969 St1egler...................242/75.53 a relatively small moton A taper tension control for 2,259,241 10/1941 066k......................242/75.51 the Winding machine.

2,886,257 5/1959 Hill 242/75 5 11 Claims, 6 Drawing Figures 1 TAPER TENSION wan WINDING MACHINE BACKGROUND OF THE INVENTION 1. Field This invention relates generally to the art of winding web material, particularly paper, paperboard or the like, into a roll. The invention relates more particularly to a taper tension web winding machine and a taper tension control for such a web winding machine.

Prior Art The winding machine of the invention is of a known class involving a web winding core driven by a DC electric motor and having speed regulation under control of a so-called dancer roller engaged in a loop in the web on its way to the core, the movement of the dancer roller with variations in tension in the web, being used to speed regulate the motor. In the past, it has been common to use such a system to maintain a constant tension in the web.

Theoretically, constant web tension is the basic requirement of winding a good roll with such a centertype winding machine. However, center-type winding machines are characterized by one phenomena which dictates against winding with constant web tension. This phenomena, commonly referred to as creep," involves axial slippage of the inner layers or turns of the web roll as the web roll diameter increases, thus resulting in a finished roll having dished ends. That is to say, one end of the roll is concave and the other end is convex.

Such "creep of the inner layers or turns of the roll result from the fact that in a center-type web winding machine, the winding torque is transmitted from the take-up core radially outward through the successive layers or windings of the roll. As a consequence, each layer transmits winding torque to the next outer layer. Moreover, to maintain constant web tension, the driving torque applied to the core must increase as the roll diameter increases. In a constant tension web winding machine, for example, the driving torque must increase in direct ratio to the roll diameter. Thus, with the core and roll diameters commonly used in the paper converting industry, i.e., core diameter 3-% inches and roll diameter 40 inches, the final and initial core driving torque for constant web tension are in the ratio (40)/(3-%) or 12 to i. This large increase in torque is transmitted through and causes both circumferential and axial slippage or creep of the inner roll layers or windings. It also causes permanent elongation of the web in many cases.

In order to wind straight rolls, that is rolls with flat, nondished ends, the web tension must be reduced, or tapered as they say in the industry, as the roll diameter increases. This latter technique of winding a web into a roll with decreasing web tension is referred to as taper tension winding, and the winding machine is referred to as a taper tension winding machine. The change decrease of the web tension from the first layer to the final layer of the finish roll is referred to as the taper ratio."

Such taper tension winding inhibits dishing of the web roll in two ways. First, taper tension winding reduces the forces exerted on the inner layers of the roll which tend to cause "creep of these layers. Secondly, taper tension winding increases the winding tension exerted on the inner layers and thereby the forces normal to the surfaces of these layers. These normal forces press the adjacent layers firmly together and thereby increase the resistance to slippage or creep of the inner layers.

A limitation in winding machines of the prior art has been the difl'iculty in winding a large diameter roll on the core. At the start of the roll, torque is low and motor speed is high, and there is a progressive transition to low speed and high torque. A large electric motor, of undesirably large inertia, is normally required to work through the extreme ranges accompanying the winding of large diameter rolls. General objectives of the invention are thus a simple, reliable system for converting the motor driven web winders of the prior art to operate with predetermined taper tension, and also a system for enabling the use of a small web driving DC motor, of low inertia, capable of operating sensitively throughout a large ratio of beginning to final roll diameters and yielding a stable final roll which has not slipped or crept, either circumferentially or axially, during the winding process.

SUMMARY OF THE INVENTION The present invention provides a taper tension web winding machine for winding a web of sheet material, particularly paper and paperboard, into a roll with a tapered tension winding action. This winding machine is generally similar to a conventional center-type web winding machine except for its web tensioning mechanism. The web tensioning mechanism of the present machine is a taper tension mechanism including a fluid-pressure-actuated web tensioning means engaging the web just before it enters onto the web roll. This tensioning means produces in the web a tension related to the fluid pressure supplied to the tensioning means.

According to the invention, the fluid pressure to the web tensioning means and hence the web tension is regulated by a fluid pressure regulating valve which is adjusted in relation to the increasing web roll diameter by a web roll diameter sensing means. This valve adjustment regulates the fluid pressure to the web tensioning means in a manner such that the web tension is reduced according to a selected or programmed taper ratio as the web roll increases in diameter. In the particular inventive embodiment selected for illustration, the valve adjusting or operating means is a cam which is driven in a prescribed valve adjusting motion by the web roll diameter sensing means and with a displacement proportional to the roll diameter.

One important feature of the invention is concerned with adjustment of the initial web tension to establish the proper initial tension for a web of given material and width such that permanent elongation of the web will not occur. This adjustment is particularly important when winding paper webs destined to be collated in register to produce endless business forms and the like. In the disclosed inventive embodiment, the initial web tension adjustment is accomplished by adjusting the operating cam for the web tension regulating valve in the direction of its prescribed valve adjusting motion independently of the web roll diameter.

Another feature of the invention is concerned with adjustment of the winding taper ratio to accommodate diflerent web materials. Thus, different materials have different optimum winding torque requirements, that is different optimum ratios of the final and initial driving or winding torques applied to the web roll. These different torque requirements necessitate difi'erent taper ratios. According to the present invention, such taper ratio adjustment is accomplished by substituting one taper tension control cam for another.

A further feature of the invention is a means controlled by web roll diameter to cut a field weakening resistor into or out of the field winding of the DC electric web roll winding motor. At the beginning of the wind, the resistor is cut into the field winding of the motor, expanding the speed range of the motor and reducing its torque range. At an intermediate point in the winding of the roll, the field resistor is cut out of the circuit of the field winding, restoring its original speed and torque ranges. Full rated torque, such as is needed for the larger diameters, is thus available, while the low speed range is restored. Thus the motor operates in two ranges, one, for the beginning in which torque is reduced, and the speed range high, and a second in which the full torque range is restored, and the speed range reduced to its original rated value. Thus a very small DC electric motor, of low horsepower, and low inertia, serves the full range from the beginning of the wind to the full diameter, with the range diameters of final diameter to core diameter expanded well beyond the normal capabilities of a small DC shunt motor.

IN THE DRAWINGS FIG. 1 is a side elevation of a taper tension winding machine according to the invention;

FIG. 2 is a view similar to FIG. 1 on enlarged scale and with parts broken away for clarity;

FIG. 3 is an enlarged section taken on line 3-3 in FIG. 2;

FIG. 4 is an enlarged section taken online 4-4 in FIG. 2;

FIG. 5 is an enlarged face view of a taper tension cam embodied in the machine; and

FIG. 6 illustrates a core driven motor control circuit embodied in the machine.

PREFERRED EMBODIMENT OF THE INVENTION The drawings illustrate a taper tension web winding machine 10 according to the invention including a basic winding machine structure 12 and a web or taper tension control mechanism 14. The basic winding machine structure 12 may conform to any conventional or special design and is shown to comprise a frame 16 including parallel upright wall members 18 rising from a mounting base 20. Rigidly joined to and extending edgewise from the wall members 18 are a pair of generally horizontal support arms 22. Extending between and removably and rotatably supported at its ends in bearings 23 on the outer ends of these arms is a rotary core 24. Core 24 is driven in rotation by a motor 26 (FIG. 6) through a releaseable drive coupling (not shown) at an end of the core. The core rotates in the clockwise direction in FIGS. 1 and 2.

The web 30 to be wound enters the machine from the left in FIGS. 1 and 2 and passes through the taper tension control mechanism 14 to the core 24. The leading end of the web is fixed to the core so that rotation of the core by its motor 26 winds the web on the core to produce a web roll 32. Web 30 may comprise any flexible sheet material which is commonly stored and handied in rolls. However, the principal application of the invention is in the paper converting industry. In this case, the web 30 will comprise paper or paperboard material which is supplied to the winding machine from a source, not shown.

The taper tension control mechanism 14 constitutes the major contribution of the present invention. In general terms this tension control mechanism comprises a fluid pressure actuated web tensioning means 34, means 36 including an adjustable pressure regulating valve 38 for supplying working fluid at a regulated pressure to the tensioning means, a web roll diameter sensing means 40, and valve operating means 42 actuated by the sensing means for adjusting the regulating valve according to a selected function of the web roll diameter. Briefly, during operation of the web winding machine the valve operating means 42 is actuated by the web roll diameter sensing means 40 to progressively adjust the pressure regulating valve 38 in response to and in accordance with the preselected function of the increasing diameter of web roll 32. This valve adjustment progressively varies the pressure of the working fluid to the web tensioning means 34 in such a manner as to cause the tensioning means to progressively relieve the tension in the web 30 at a programmed rate which yields the desired taper ratio.

Referring now in greater detail to the particular taper tension winding machine selected for illustration, the web tensioning means 34 comprises a pair of idler rollers 44, 46 extending between the frame wall members 18 parallel to the windup core 24 and rotatably supported at their ends on the wall members. Between, below, and parallel to the idler rollers in a floating dancer roller 48. The ends of the dancer roller are rotatably supported on the outer ends of a pair of arms 50. The opposite ends of these arms are keyed to a shaft 52 extending between and rotatably supported in the wall members 18. Arms 50 and shaft 52 pivotally support the dancer roller 48 for vertical swinging movement about an axis parallel to the dancer roller, idler roller, and core axes.

The web 30 to be wound enters the winding machine from the left in FIGS. 1 and 2 and passes over the idler roller 44, then downwardly around the underside of the dancer roller 48, then upwardly over the idler roller 46, and finally to the web roll 32.

The near end of shaft 52 in FIGS. 1 and 2 extends through and beyond the adjacent frame wall member 18. Fixed at one end to this outboard end of the shaft is an arm 54. A fluid pressure actuator 56 is connected between the machine base 20 and the outer end of arm 54. The illustrated actuator is a single acting pneumatic actuator having a cylinder 58 pivotally attached at its lower end to the base and a plunger 60 pivotally attached at its upper end to the arm 54. At the upper end of the cylinder is an inlet 62 for pressure air. At the lower end of the cylinder is a vent 64. Pressure air supplied to the cylinder 58 through its inlet 62 urges the plunger 60 downwardly in the cylinder, thereby urging the dancer roller 48 downwardly about its pivot axis to tension the web 30.

Pressure air is supplied to the cylinder 58 through an air line 66 which connects to the cylinder'air inlet 62.

The pressure regulating valve 38 is connected in this air line to regulate the air pressure to the cylinder and thereby the tension in the web 30. Valve 38 is a conventional air pressure regulating valve including a body 68 which is attached to the near frame wall 18 in FIGS. 1 and 2. Movable in and projecting from the upper end of the valve body is an upwardly spring biased pressure regulating member 70. On the upper end of regulating member is a roller 72 having its axis normal to the frame walls 18.

Downward displacement of the pressure regulating member 70 relative to the valve body 68 increases the air pressure to the web tensioning cylinder 58 and hence the tension in the web 30. Upward displacement of the member reduces the air pressure to the cylinder and the web tension.

Valve operating means 42 comprises a disc cam 76 fixed on a shaft 78 which is rotatably mounted on the near frame wall 18 in FIGS. 1 and 2. Cam 76 is located directly over the pressure regulating valve 38 with the cam rotation axis intersecting at right angles to the axis of the valve regulating member 70. The edge 82 of the cam bears against the upper side of the valve roller 72.

Turning to FIG. 5, it will be seen that the cam 76 has a radius R from its rotation axis a to its edge 82 which remains constant along a low dwell portion 82a of the edge, then progressively increases (in the clockwise direction about the cam as the latter is viewed in FIG. 5) along a major central portion 82b of the cam edge, and finally remains constant along a high dwell portion 820 of the edge. As will be explained presently, the cam dwell portions 820, 820, are provided to permit constant tension winding operation of the machine. The following discussion relates to taper tension winding operation which uses only the sloping cam.portion 82b. In this latter winding mode, the valve roller 72 engages the sloping cam portion through the entire winding operation so that clockwise rotation of the cam in FIGS. 1 and 2 causes the fluid pressure to the web tensioning cylinder 58 and thereby the web tension to progressively diminish to a constant rate determined by the slope of the sloping cam edge portion.

The web roll diameter sensing means 40 comprises an arm 84 fixed at one end to a bracket plate 86 interposed between one end of the idler roller 46 and the adjacent frame wall 18. This plate is rotatably supported between its ends on the central roller support shaft 87. Pivotally connected at one end to the end of the bracket plate 86 remote from the sensor arm 84 is a link 88. The opposite end of the link 88 is pivotally attached to the outer end of an arm 90 keyed on the cam shaft 78. Sensor arm 84 is vertically swingable in a plane located beyond, i.e., in front of in FIGS. 1 and 2, the adjacent end of the web roll 32. Rotatable on the outer end of the arm on an axis parallel to the roll axis is a roller 92 which rests on the outer layer of the web roll 32.

From this description it is evident that during winding operation of the machine, the sensor arm 84 is upwardly rotated in the counterclockwise direction in FIGS. 1 and 2 as the web roll 32 increases in diameter. This upward rotation of the arm rotates the cam 76 in the clockwise direction in direct ratio to the web roll diameter and through a total angle proportional to the difference in diameters of the core 24 and the finished web roll 32. For reasons to be explained presently, this total angle of cam rotation is substantially less than the angular extent of the sloping cam edge portion 82b.

This clockwise rotation of the cam progressively reduces the air pressure to the web tensioning cylinder 58 and thereby the tension in web 30.

For reasons to be explained presently, the cam 76 is removable from its shaft 78 for replacement by a cam of different profile. Also, the cam is rotatably adjustable independently of the position of the web roll diameter sensor arm 84. To these ends, the cam is releaseably secured to the shaft by a nut 94 which may be loosened to rotatably adjust the cam and removed to replace the cam.

As noted earlier, during winding operation of the machine, the driving torque of the take up core drive motor 26 is increased and the rotational speed of the motor is reduced as the web roll diameter increases in order to permit the use of a relatively small drive motor. This this end, the machine is provided with a motor control circuit 96 (FIG. 6) for reducing the motor speed and increasing the motor torque at a selected web roll diameter which may be on the order of one third to one half the diameter of the finished roll. The drive motor 26 shown is a D. C. motor. The motor control circuit 96 comprises a resistance 98 connected in series with the motor field winding 100 and in parallel with a normally closed switch 102. Referring to FIGS. 1 and 2, switch 102 is mounted below the sensor arm bracket plate 86 in a position such that the lower edge of the plate engages and retains the switch open during upward rotation of the roll diameter sensor arm 84 from its initial winding position to the position corresponding to the roll diameter at which the motor torque and speed are to be changed. At this point, the plate releases the switch for return of the latter to its normally closed position. When switch 102 occupies its initial open position, the resistance 98 limits the voltage applied to the motor field 100 and the motor 26 has maximum speed well above rated base speed and a reduced driving torque. Closure of the switch in response to web roll build up to the selected diameter shunts out the field resistance to reduce maximum motor speed to rated base speed and to restore maximum rated torque capabilities.

In operation of the taper tension winding machine, the leading end of the web 30 is fixed to the take up core 24 and the motor 26 is energized to wind the web on the core. Initially, the web roll diameter sensor arm 84 occupies its lower core diameter position shown in broken lines in FIG. 2, and the motor field switch 102 is open. Under these conditions, the resistance 98 is placed in series with the motor field 100 to increase the speed and reduce the driving torque of the motor. Also, the valve adjusting cam 76 occupies its limiting position of counterclockwise rotation by the arm 84. In this position, the pressure regulating valve 38 supplies air under relatively high pressure to the web tensioning cylinder 58 to produce a relatively high initial tension in the web 30. As noted earlier and explained in more detail shortly, this initial web tension is adjustable by rotating the valve cam 76 relative to its supporting shaft 78 The build up in the web roll 32 during the winding operation causes the arm 84 to gradually rotate upwardly. This rotation of the arm rotates the valve cam 76 clockwise to progressively reduce the air pressure to the web tensioning cylinder 58 and hence the tension in the web 30. When the web roll 32 attains the diameter at which the maximum motor speed and torque of the core drive motor 26 are to be changed, the motor field switch 102 closes to reduce the maximum motor speed range and to restore full rated motor torque.

According to the present invention, the valve cam 76 is designed to progressively reduce the tension in the web 30 at the rate required to achieve a desired taper ratio. In this regard, one aspect of the invention involves the discovery that the torque applied to the innermost layer or winding of the web roll 32, when winding paper or paperboard must not exceed a ratio of 6:1 from the core to the finished roll; that is to say, when winding paper or paperboard, elimination of slippage or creep of the inner web roll layers or windings requires that the final torque transmitted through the innermost layer to the outer most layer of the finished web roll at the conclusion of the winding not exceed six times the torque applied to the inner most layer at the start of winding.

From this, the following empirical formula for the taper ratio may be derived:

( H/ c) X T Where: D, is the diameter of the largest web roll to be wound.

D, is the take-up core diameter.

Tis the taper ratio.

The valve adjusting cam 76 is designed to produce this taper ratio. This is accomplished by providing the cam edge portion 82b with a unifonn slope such that rotation of the cam from its initial position to its final position when winding the largest diameter roll progressively reduces the web tension at the rate required to attain the taper ratio established by the above empirical formula. It will be obvious, of course, that if the cam 76 provides the proper taper ratio for the largest diameter web roll, it will also provide the proper taper ratio for all smaller diameter web rolls.

The above discussion relates only to paper and paperboard whose maximum permissable torque requirements for flat roll winding are in the stated 6:1 torque ration. However, the maximum permissable torque ratio for other web materials may be determined and substituted in the emperical taper ratio formula to determine the proper taper ratio for flat roll winding. A valve cam 76 may then be generated with the correct profile or or slope to achieve this taper ratio.

It will now be understood that the present taper tension winding machine may be adopted to wind a variety of web materials requiring different taper ratios by providing a set of valve adjusting or taper tension cams of the proper profile or slope. In this regard, it is significant to recall that the cam 76 is removable from its shaft 78 to permit its replacement by another cam.

As noted earlier another requirement which must be satisfied when winding many web materials, notably paper webs to be collated in registry to produce endless business forms or the like, is the prevention of permanent web elongation. In order to prevent such permanent elongation the air pressure to the web tensioning cylinder 58 must be adjusted to establish in the web 30 an initial tension at the start of winding which is less than the critical web tension required to produce permanent web elongation. It will be immediately evident that the air pressure to the cylinder necessary to establish the proper initial web tension will vary according to the width, thickness, and material of the web and other factors. Means must be provided therefore, for adjusting the cylinder air pressure.

According to a feature of the present invention, such air pressure adjustment is accomplished by rotating the valve cam 76 relative to its shaft 78 and the web roll diameter sensor arm 84. In this regard, it will be recalled that the cam is releasable for such rotary adjustment. This cam adjustment obviously increases or decreases, depending upon the direction of cam rotation, the air pressure to the cylinder 58 and thereby the web tension without altering the taper ratio established by the cam. According y, the present taper tension winding machine may be conditioned to wind any web material into a flat roll without permanent web elongation by selecting a cam 76 of the proper taper ratio and adjusting the cam to provide the proper initial web tension. In connection with this cam adjustment, it is significant to recall that the maximum angle of the cam rotation during winding operation of the machine, that is, the angle through which the cam rotates when winding the largest web roll, is substantially less than the total angular extent of the sloping cam edge portion 82b. The excess cam edge length is provided to permit the above initial cam adjustment. If desired, each cam may have a scale for quick reference in selecting the desired tension range.

When winding a very thin web, it is desirable to cushion any sudden tension increase in the web in order to prevent parting of the web. To this end, the winding machine is equipped with a shock absorber 104 which, in this instance, is a fluid shock absorber connected between the machine base 20 and the dancer roller torque arm 54.

According to another feature of the invention, a quick dump valve 106 is connected in the air line 66 between the web tensioning cylinder 58 and pressure regulating valve 38. This dump valve is provided to remove or vent sudden pressure surges resulting from rapid start-ups and stops and thereby permit the dancer roller 48 to rapidly assume its proper operating position without excessive increase in web tension.

It will be recalled that the motor 26 drives the core 24 through reduction gearing. This reduction gearing cooperates with the motor field resistor 98 and its shunting switch 102 to permit utilization of a relatively small motor (i.e., 7 horse power) to provide the required high core speed at the start of winding and thus the high drive torque required for finishing of winding. Thus, the reduction gear is selected to provide the proper drive speed to the core during the first part of the winding operation, when the motor speed is increased well above the rated base speed by motor field weakening, and its output torque is reduced proportionately. Shunting of the field resistor 98 by closure of switch 102 at an intermediate roll diameter restores the maximum motor output torque to provide the higher core driving torque during the final portion of the winding operation.

weakening of the D. C. motor by the field resistor 98 results in extension of the maximum motor speed range well above the rated motor speed and proportionate reduction of motor torque. This permits a higher gearin ratio between motor and rewind core. Shunting of the field resistor 98 by closure of switch 102 at an intermediate roll diameter restores the higher rated motor torque and reduces the maximum motor speed to rated speed. The higher gear-in ratio increases the torque available at the rewind roll. For example; if the web speed is constant, the beginning roll speed is 1,000 RPM and rated motor base speed is 2,500 RPM, then the maximum mechanical gear-in ratio is 2,500/1,000 2.5/1, that is, the maximum torque available at the winding roll is 2% times the rated motor torque. In this case, the motor speed would be 2,500/ l2 208%; RPM at a final roll diameter 12 times the starting roll diameter. However, by utilizing the field weakening resistor 98 at the start of winding the maximum speed of the field weakening motor at the start of winding may be increased to, say, 4,000 RPM, thereby permitting a mechanical gear-in ratio between motor and winding core of 4,000/1,000 4/1. This field weakening reduces the motor torque by a ratio of 2,500/4,000 of rated torque. This is so because the D. C. motor delivers a constant rated torque from zero speed to its maximum rated base speed and a constant horse power at field weakened speeds above the rated base speed. The higher gear-in ratio (4/1 vs. 2-%/ l) multiplies the torque delivered to the winding roll so that the torque available at the winding roll is not reduced even when the field weakening of the motor is in effect. As soon as the field weakening resistor is shunted at the intermediate winding roll diameter, full rated motor torque is restored, and the torque available at the roll is now four times the rated motor torque vs. 2-5; times if no field weakening were used. At the final roll diameter, the motor speed now is 4,000/12 333-!!! RPM. It is apparent from the above that the horsepower available at the final roll diameter is now 8/5 or 1.66 times that available if field weakening were not employed at the start of the winding. Consequently, the drive motor needs to have only a horsepower rating of /8 of that which would be required if the field weakening resistor of this invention were not utilized at the start of winding. Furthermore, the higher motor speed results in increased volume of cooling air being forced through the motor at the higher motor speeds and results in cooler running motor with less danger of motor bum-out.

The description to this point has related only to operation of the present winding machine in its taper tension winding mode. However, the illustrated machine is also capable of operation in a constant tension winding mode. In this regard, it will be recalled that cam 76 has low and high dwell portions 820, 82c of constant radius. Constant tension winding operation of the machine is accomplished by adjusting the cam to an initial winding position such that either dwell portion of the cam remains in contact with the roller 72 on the pressure regulating valve 38 during the entire winding operation and by adjusting the fluid pressure to the proper level for constant tension winding. The machine then proceeds through its winding operation in the same manner as described earlier except that the cam 76 maintains a constant fluid pressure to the web tension cylinder 58 and hence a constant web tension.

We claim:

1. A taper tension winding machine for winding a web of sheet material into a roll, comprising:

a frame,

a rotary take-up core on said frame to which the leading end of said web is adapted to be secured,

a DC electric motor for driving said core in rotation to wind said web into a roll on said core,

movable fluid pressure actuated web tensioning means engageable with said web ahead of said core for producing in the portion of the web extending from said tensioning means to said roll a tension related to the fluid pressure supplied to said tensioning means; and

means responsive to increase in diameter of the web roll for progressively changing said fluid pressure in a manner to reduce said web tension.

2. The subject matter of claim 1, wherein said electric motor is a DC shunt motor whose field winding includes a field weakening resistor, and means responsive to winding roll diameter for automatically placing said resistor in series circuit with said field resistor in an early stage of the winding of said web onto said core, and responsive to growth of the diameter of said roll, to an intermediate diameter to thereafter shunt out said resistor.

3. A taper tension winding machine for winding a web of sheet material into a roll, comprising:

a frame;

a rotary take-up core on said frame to which the leading end of said web is adapted to be secured;

a DC electric motor for driving said core in rotation to wind said web into a roll on said core;

movable fluid pressure actuated web tensioning means engageable with said web ahead of said core for producing in the portion of the web extending from said tensioning means to said roll a tension related to the fluid pressure supplied to said tensioning means;

an adjustable fluid pressure regulator for regulating said fluid pressure; and

regulator adjusting means, including means for sensing the diameter of the web roll, for adjusting said regulator in response to said sensor to reduce the said fluid pressure progressively with growth in the diameter of the web roll.

4. The subject matter of claim 3, wherein said regulator adjusting means includes a cam follower, and a cam movable thereagainst in response to growing diameter of the web roll as sensed by said sensor.

5. The subject matter of claim 4, wherein the cam is a rotary cam of progressively changing radius, said cam being adjustable about its axis of rotation relative to said cam follower independently of the diameter of the roll of paper on said core to modify the portion of the cam in operative relationship with the cam follower.

6. The subject matter of claim 5, wherein said cam is rotatable on a fixed axis, and has a peripheral cam surface in operative engagement with said cam follower, said cam surface having a first arcuate extent which is of progressively increasing radius, said cam being adjustable on its axis of rotation independently of the diameter of the roll of paper on said core.

7. A taper tension winding machine for winding 21 web of sheet material into a roll, comprising:

a frame;

a rotary take-up core on said frame to which the leading end of said web is adapted to be secured;

a DC electric motor for driving said core in rotation to wind said web into a roll on said core;

movable fluid pressure actuated web tensioning means engageable with said web ahead of said core for producing in the portion of the web extending from said tensioning means to said roll a tension related to the fluid pressure supplied to said tensioning means;

an adjustable fluid pressure regulator for regulating said fluid pressure, said regulator comprising a fluid pressure regulating valve including a pressure regulating member movable in one direction to increase said fluid pressure and in the opposite direction to reduce said fluid pressure;

means for sensing the diameter of said web roll;

regulator adjusting means for said regulating member of said valve for progressively changing said fluid pressure in a sense to reduce said web tension;

said regulator adjusting means comprising a rotary cam; and

said sensing means comprising a web roll diameter sensor arm pivoted at an end of said frame and engaging the outer layer of said roll at its other end, such that said arm rotates in one direction in response to the increasing diameter of said roll, and means connecting said arm and cam whereby rotation of said arm in said one direction rotates said cam in one direction.

8. The winding machine according to claim 7 wherein:

said web tensioning means comprises a pair of idler rollers on said frame around which said web passes, a floating dancer roller engageable with said web between said rollers, and an actuator connected to said dancer roller for urging said latter roller against said web with a force proportional to the regulated fluid pressure.

9. The subject matter of claim 8 including:

means actuated by said sensor arm at a selected intermediate web roll diameter for regulating said motor to increase its torque and reduce its speed.

10. The subject matter of claim 9, wherein said electric motor is a DC shunt motor whose field winding includes a field weakening resistor; and

means responsive to winding roll diameter for automatically placing said resistor in series circuit with said field resistor in an early stage of the winding of said web onto said core, and responsive to growth of the diameter of said roll, to an intermediate diameter to thereafter shunt out the resistor.

1 l. The subject matter of claim 7, wherein:

said cam has a portion of progressively varying radius for taper tension winding operation and at least one constant radius portion for constant tension winding operation; and

means for rotatably adjusting said cam to a portion wherein either of said cam portions is effective to control web tension during winding operation of said machine.

* i I t 

1. A taper tension winding machine for winding a web of sheet material into a roll, comprising: a frame, a rotary take-up core on said frame to which the leading end of said web is adapted to be secured, a DC electric motor for driving said core in rotation to wind said web into a roll on said core, movable fluid pressure actuated web tensioning means engageable with said web ahead of said core for producing in the portion of the web extending from said tensioning means to said roll a tension related to the fluid pressure supplied to said tensioning means; and means responsive to increase in diameter of the web roll for progressively changing said fluid pressure in a manner to reduce said web tension.
 2. The subject matter of claim 1, wherein said electric motor is a DC shunt motor whose field winding includes a field weakening resistor, and means responsive to winding roll diameter for automatically placing said resistor in series circuit with said field resistor in an early stage of the winding of said web onto said core, and responsive to growth of the diameter of said roll, to an intermediate diameter to thereafter shunt out said resistor.
 3. A taper tension winding machine for winding a web of sheet material into a roll, comprising: a frame; a rotary take-up core on said frame to which the leading end of said web is adapted to be secured; a DC electric motor for driving said core in rotation to wind said web into a roll on said core; movable fluid pressure actuated web tensioning means engageable with said web ahead of said core for producing in the portion of the web extending from said tensioning means to said roll a tension related to the fluid pressure supplied to said tensioning means; an adjustable fluid pressure regulator for regulating said fluid pressure; and regulator adjusting means, including means for sensing the diameter of the web roll, for adjusting said regulator in response to said sensor to reduce the said fluid pressure progressively with growth in the diameter of the web roll.
 4. The subject matter of claim 3, wherein said regulator adjusting means includes a cam follower, and a cam movable thereagainst in response to growing diameter of the web roll as sensed by said sensor.
 5. The subject matter of claim 4, wherein the cam is a rotary cam of progressively changing radius, said cam being adjustable about its axis of rotation relative to said cam follower independently of the diameter of the roll of paper on said core to modify the portion of the cam in operative relationship with the cam follower.
 6. The subject matter of claim 5, wherein said cam is rotatable on a fixed axis, and has a peripheral cam surface in operative engagement with said cam follower, said cam surface having a first arcuate extent which is of progressively increasing radius, said cam being adjustable on its axis of rotation independently of the diameter of the roll of paper on said core.
 7. A taper tension winding machine for winding a web of sheet material into a roll, comprising: a frame; a rotary take-up core on said frame to which the leading end of said web is adapted to be secured; a DC electric motor for driving said core in rotation to wind said web into a roll on said core; movable fluid pressure actuated web tensioning means engageable with said web ahead of said core for producing in the portion of the web extending from said tensioning means to said roll a tension related to the fluid pressure supplied to said tensioning means; an adjustable fluid pressure regulator for regulating said fluid pressure, said regulator comprising a fluid pressure regulating valve including a pressure regulating member movable in one direction to increase said fluid pressure and in the opposite direction to reduce said fluid pressure; means for sensing the diameter of said web roll; regulator adjusting means for said regulating member of said valve for progressively changing said fluid pressure in a sense to reduce said web tension; said regulator adjusting means comprising a rotary cam; and said sensing means comprising a web roll diameter sensor arm pivoted at an end of said frame and engaging the outer layer of said roll at its other end, such that said arm rotates in one direction in response to the increasing diameter of said roll, and means connecting said arm and cam whereby rotation of said arm in said one direction rotates said cam in one direction.
 8. The winding machine according to claim 7 wherein: said web tensioning means comprises a pair of idler rollers on said frame around which said web passes, a floating dancer roller engageable with said web between said rollers, and an actuator connected to said dancer roller for urging said latter roller against said web with a force proportional to the regulated fluid pressure.
 9. The subject matter of claim 8 including: means actuated by said sensor arm at a selected intermediate web roll diameter for regulating said motor to increase its torque and reduce its speed.
 10. The subject matter of claim 9, wherein said electric motor is a DC shunt motor whose field winding includes a field weakening resistor; and means responsive to winding roll diameter for automatically placing said resistor in series circuit with said field resistor in an early stage of the winding of said web onto said core, and responsive to growth of the diameter of said roll, to an intermediate diameter to thereafter shunt out the resistor.
 11. The subject matter of claim 7, wherein: said cam has a portion of progressively varying radius for taper tension winding operation and at least one constant radius portion for constant tension winding operation; and means for rotatably adjusting said cam to a portion wherein either of said cam portions is effective to control web tension during winding operation of said machine. 